1. Field of the Invention
This invention relates to a method of and apparatus for opening scores in a glass sheet and more particularly to opening lateral scores in a moving annealed glass ribbon.
2. Discussion of Technical Problems
As is known in the glass art, a continuous glass ribbon is advanced from an annealing lehr through a scoring station and a snapping station to sever the glass ribbon into pieces or caps of a predetermined size.
The cut edge of the glass pieces or caps are preferably free of damage due to score opening. In other words, it is preferred that the cut edge have only scoring damage and not score opening or severing damage because cut edge damage due to scoring is controllable and therefore the quality of the glass cut edge can be controlled. However, cut edge damage resulting from score opening is not controllable.
Cut edge damage resulting from score opening is due to the stress pattern in the glass ribbon. More particularly, the edges of the glass ribbon are in compression relative to the ribbon center which is in tension. The compressive stresses at the ribbon edges counteract the bending moments applied about the score. When the glass is severed along the score line, the resulted cut edge is jagged, i.e., has shark teeth. This damage is removed by grinding, seaming or another cutting operation to increase the cut edge strength of the glass.
It would be advantageous, therefore, to provide an apparatus for and method of opening score lines in a glass ribbon such that the cut edge of the glass has only score damage.